Device to convey fibers to the fiber collection groove of an open-end spinning rotor

ABSTRACT

The instant invention relates to a device for the feeding of fibers (51) to the fiber collection groove (23) of an open-end spinning rotor (2). The latter is covered by a rotor cover (3) whose side toward the spinning rotor (2) contains a fiber guiding element (8) the inner circumferential surface (12) of which, in form of a fiber guiding surface, forms a divergence angle (W1) widening in the direction of the spinning rotor (2). The fiber guiding element (8) extends coaxially into the spinning rotor (2). A fiber feeding channel (14) lets out tangentially into its inner circumferential surface (12).

BACKGROUND OF THE INVENTION

The present invention relates to a device to convey fibers to the fibercollection groove of an open-end spinning rotor with a fiber guidingelement extending coaxially into the spinning rotor and provided with aninner circumferential surface in the form of a fiber guiding surfaceinto which a fiber feeding channel lets out tangentially.

In a known device of this type (DE-OS 2,319,428) a channel-shaped fiberguiding element is provided, along the circumferential wall of which thefibers are conveyed in a spiral to the spinning rotor. This channel hasa cylindrical cross-section or a cross section representing asubstantial portion of its length and tapering in the direction of thespinning rotor. Such a channel-shaped fiber guiding element not onlyrequires much space but also has most certainly no positive influence onthe fiber feeding into the spinning rotor. It has been shown forexample, that the fibers become caught in the channel-shaped fiberguiding element and even lead to clogging. This known device couldtherefore not be introduced in practice.

OBJECTS AND SUMMARY OF THE INVENTION

It is therefore a principal object of the instant invention to create adevice which is space saving and makes it possible to achievetrouble-free spinning operation as well as the production ofhigh-quality yarns. Additional objects and advantages of the inventionwill be set forth in part in the following description, or may beobvious from the description, or may be learned by practice of theinvention.

The objects are attained through the invention in that the spinningrotor is covered by a rotor cover whose side towards the spinning rotorcontains the fiber guiding element, the inner circumferential surface ofwhich includes a divergence angle opening in the direction of thespinning rotor. The fiber guiding element is in this case so small andcompact that it fits in the rotor cover. The invention furthermoreensures undisturbed fiber feeding into the spinning rotor since itswidening inner circumferential surface imparts a motion component indirection of the spinning rotor to the air which conveys the fibers andthereby also to the fibers themselves. Catching of the fibers due tocentrifugal force is thereby prevented.

To make low-cost fabrication possible, the fiber guiding element isadvantageously an integral part of the rotor cover.

In an easily fabricated embodiment of the invention, the innercircumferential surface of the fiber guiding element widens in themanner of a cone in the direction of the spinning rotor.

The divergence angle increases preferably from the outlet of the fiberfeeding channel in the direction of the spinning rotor. In this manner,the friction effect which is produced by the inner circumferentialsurface of the fiber guiding element upon the fibers is counteracted sothat even when the distance between the outlet of the fiber feedingchannel and the spinning rotor is greater, fibers are reliably preventedfrom catching on the fiber guiding element.

In an advantageous embodiment of the device according to the inventionthe enlargement of the divergence angle is continuous, whereby the innercircumferential surface of the fiber guiding element is preferablyarched in a convex manner.

In another advantageous embodiment of the invention, the increase of thedivergence angle is discontinuous, i.e. in steps. In this case, theinner circumferential surface of the fiber guiding element is preferablycomposed in the axial direction of at least two longitudinal segmentswith different divergence angles. It has been shown to be advantageousfor the longitudinal segment into which the fiber feeding channel letsout to be made in the form of a conical surface. The longitudinalsegment of the fiber guiding element which is towards the spinning rotorcan also be made in the form of a conical surface in that case.

In another advantageous embodiment of the invention, an additionalconvex longitudinal segment is provided between two conical longitudinalsegments of the inner circumferential surface of the fiber guidingelement.

In order to make it possible to easily exchange different spinningrotors being used optionally while space availability remains unchangedbetween an opener unit and the feeding device and the spinning rotor,provisions may be made in an advantageous embodiment of the inventionfor the longitudinal segment of the fiber guiding element towards thespinning rotor to be replaceable.

To ensure especially secure fiber transfer to the gliding wall of thespinning rotor, the invention advantageously provides for the fiberguiding element to protrude into the spinning rotor.

The term "cone" or "conical" does not only designate themathematical/geometrical concept of a cone in itself, but also truncatedcones and other cone-like configurations in the sense of the invention.

The design of the fiber guiding element in accordance with the inventionnot only makes it possible to achieve a significant technical success inthe feeding of the fibers into the spinning rotor and thereby animprovement of yarn values, but the spinning device can be given a morecompact configuration. It has been shown that the inner circumferentialsurface need not be very long in the axial direction. The distancebetween the outlet of the fiber feeding channel and the open edge of thefiber guiding element extending into the spinning rotor can be merelysufficiently great so that the fibers are able to collect in the airstream which is conveyed along the inner circumferential surface in theform of a spiral to the spinning rotor, so that they reach the spinningrotor at a contour line determined by the edge of the fiber guidingelement. In this manner, good yarn values from the point of view ofuniformity, strength, and elasticity are obtained. The invention canvery easily be retrofitted in all current rotor spinning devices, andfor this it generally suffices to replace the rotor cover.

Examples of embodiments of the invention are explained below throughdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a cross-section of an open-end spinning device with a rotorcover designed according to the invention, with integrated fiber guidingelement; and

FIGS. 2a to 2d schematically show different configurations according tothe invention of the inner circumferential surface of the fiber guidingelement integrated into rotor cover.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the presently preferredembodiments of the invention, one or more examples of which areillustrated in the drawings. Each example is provided by way ofexplanation of the invention, not limitation of the invention. Thenumber of components is consistent throughout the description anddrawings, with the same components having the same number throughout.

FIG. 1 shows the essential part of a conventional open-end rotorspinning device, and in it only the parts thereof which are necessary tounderstand the invention are shown.

The rotor spinning device, of which normally a plurality are placed nextto each other in a spinning machine, is provided with a housing 1 inwhich spinning rotor 2 capable of being driven in the direction of arrowP is rotatably mounted in a manner not shown here by means of a shaft 7.The spinning rotor is normally provided with a gliding wall 22 wideningfrom an open edge 9 to a fiber collection groove 23.

The housing 1 is provided with a rotor cover 3 covering the open side ofthe spinning rotor 2 and is connected by its interior space via an airline 4 to a source of negative pressure (not shown) to produce thenegative spinning pressure.

A yarn draw-off pipe 6, which is located in the shown embodiment in theshaft 7 of the spinning rotor 2 made in the form of a hollow shaft andextending into the spinning rotor 2, is used to remove the yarn 5 fromthe spinning rotor 2.

A fiber guiding element 8 is installed in the rotor cover 3 on its sidetoward the spinning rotor 2 and coaxial with the spinning rotor 2, sothat the geometric axis A of the fiber guiding element 8 coincides therotational axis of the spinning rotor 2. This fiber guiding element 8 isan integral part of the rotor cover 3 and extends into the spinningrotor 2, whereby it ends with its outlet opening 10 inside the open edge9 of the spinning rotor 2. The diameter of the fiber guiding element 8is here close to the diameter of the open edge 9 of the spinning rotor2. At its end away from the spinning rotor 2, the fiber guiding element8 is closed by a forward wall 11.

The fiber guiding element 8 is provided with an inner circumferentialsurface 12 which serves as a fiber guiding surface and extends from theforward wall 11 of the fiber guiding element 8 to the outlet opening 10.

Within the inner circumferential surface 12 of the fiber guiding element8 and at a distance from its outlet opening 10 is the outlet 13 of afiber feeding channel 14 which starts at an opener and feeding unit 15and merges tangentially into the inner circumferential surface 12. Thisfiber feeding channel 14 and its outlet 13, as well as the fiber guidingelement 8, are designed so that an air stream is produced and introducedtangentially into the fiber guiding element 8 in the direction ofrotation of the spinning rotor 2 as a result of the negative pressure inthe air line 4, whereby the air stream carries along the fibers 51 andfeeds them tangentially to the inner circumferential surface 12. Thisair stream leaves the spinning rotor 2 again through the gap between theopen edge 9 of the spinning rotor 2 and the fiber guiding element 8.

As FIG. 1 shows, the inner circumferential surface 12 widens in itsentirety from the forward wall 11 to the outlet opening 10, i.e. theinner circumferential surface 12 thereby includes a divergence angle W1.Different versions of the special configuration of the innercircumferential surface 12 are possible and these depend on the spinningconditions, i.e. on different factors such as rotor speed, control offiber feeding speed etc. Thus, this inner circumferential surface 12widens according to FIG. 1 in the form of a cone or of a truncated cone.However, it may also be continuously curved for example, as shown inFIG. 2a (see curvature radius R) or it may consist of a conical (ortruncated-conical) longitudinal segment 16 and a continuously curvedlongitudinal segment 17 which follows this first conical longitudinalsegment 16 and extends to the outlet opening 10 (FIG. 2b).Alternatively, the inner circumferential surface 12 may also consist ofat least two conical or truncated-conical longitudinal segments 18, 19following each other as shown in FIG. 2c. According to another possibledesign, a curved longitudinal segment 20 is provided between at leasttwo such conical longitudinal segments 18, 19 (FIG. 2d). Each of theseinner circumferential surfaces 12 according to FIG. 1 or one of theFIGS. 2a to 2d diverges in the direction of the spinning rotor 2. Thisinner circumferential surface 12 is advantageously provided with adivergence angle W1 at least at location 21 where the fibers 51 leavethe inner circumferential surface 12 during operation, the divergenceangle W1 being greater than the divergence angle W2 of the ensuinggliding wall 22 of the spinning rotor 2.

In principle any of the configurations of the illustrated innercircumferential surface 12 advantageously ensures secure fibertransportation from the outlet 13 of the fiber feeding channel 14 to thegliding wall 22 of the spinning rotor 2. Thanks to the wideningconfiguration of the inner circumferential surface 12 of the spinningrotor 2, the air with the fibers 51 which is conveyed to the spinningrotor 2 in circumferential direction of the inner circumferentialsurface 12 is gradually accelerated so that the resultant airstreamconveys the fibers 51 to the outlet opening 10 of the fiber guidingelement 8 while overcoming friction.

The velocity of the air which conveys the individual fibers 51, and itsacceleration, depend not only on the conicity, i.e. the divergence angleW1 of the fiber guiding element 8, but substantially also on the speedwith which the air again leaves the spinning rotor 2. This speed can besized or controlled by means of an external source of negative pressurewhich aspires air from the spinning rotor 2 through the air line 4.

The configuration of the inner circumferential surface 12 in the form ofa cone or truncated cone is especially easy to produce. The length ofthe inner circumferential surface 12 in the axial direction of the fiberguiding element 8 may be varied and depends essentially on the speed ofthe air stream conveying the individual fibers 51 and on the divergenceangle W1. The lesser the air speed and the lower the divergence angleW1, the lower this length must be. If however the distance between theoutlet 13 of the fiber feeding channel 14 and the outlet opening 10 ofthe fiber guiding element 8 is greater, it is especially advantageous ifthe greater friction acting upon the fibers 51 which is produced becauseof the longer distance is compensated for by increasing the divergenceangle W1 from the outlet 13 of the fiber feeding channel 14 in thedirection of the spinning rotor 2 and/or by increasing the air speed.The increase of the divergence angle W1 may be continuous, in uniform ornon-uniform manner. Thus, as mentioned earlier in connection with FIG.2a, the inner circumferential surface 12 of the fiber guiding element 8may be uniformly arched in a convex manner.

According to FIGS. 2b to 2d, the enlargement of the divergence angle isdiscontinuous. According to FIGS. 2b and 2c two longitudinal segments 16and 17 or 18 and 19 with different divergence angles W1 are provided forthis. For manufacturing reasons the longitudinal segment 16 or 18 inwhich the outlet 13 of the fiber feeding channel 14 is located ispreferably made in the form of a conical surface, by which also asurface in the form of a truncated cone is to be understood.

According to FIGS. 2c and 2d the longitudinal segment 19 of the innercircumferential surface 12 of the fiber guiding element 8 towards thespinning rotor 2 is also in the form of a conical surface. As mentionedearlier, the conical configuration can be produced very easily, e.g. bylathing.

The transition from one longitudinal segment to the next isdiscontinuous when two conical (or truncated-conical) longitudinalsegments 18 and 19 follow each other (see FIG. 2c). If such a divergencediscontinuity is to be avoided, e.g. in order to achieve a more uniformflow and thus to accelerate and stretch the fibers 51 continuously andin order to thus achieve optimal gliding of the individual fibers 51,the transition between these longitudinal segments 18 and 19 can be moregentle, in that an additional, convexly curved longitudinal segment 20is provided between these two conical longitudinal segments 18 and 19.

During spinning operation, the opener and feeding device 15 is fed afiber sliver (not shown) which is opened into individual fibers 51.Since air is aspired from the interior of the housing 1 during theoperation of the described device as indicated earlier, an air streamwhich enters the fiber guiding element 8 in tangential direction in thesense of rotation of the spinning rotor 2, but with a deviation indirection of the spinning rotor 2 is produced as a result of thissuction. The air stream is imparted a helicoidal movement in thismanner, whereby this air stream has at the same time an axial motioncomponent along the inner circumferential surface 12. The fibers 51 aretaken up by the aforementioned air stream and are conveyed in suchmanner that they move in a straightened state with one fiber end aheadof the other. During the helicoidal movement of the air stream thecentrifugal forces begin to act upon the fibers 51 which reach the innercircumferential surface 12 in a boundary layer. Since this innercircumferential surface 12 diverges in the direction of the spinningrotor 2, the centrifugal forces produce an axial force which causes thefibers 51 to move along the inner circumferential surface 12 in thedirection of the spinning rotor 2. These axial components caused by thecentrifugal force acts first upon the forward ends of the fibers 51 sothat said fibers 51 are stretched and straightened during theirtransportation.

The air stream conveying the fibers moves, thanks to its guidancethrough the diverging inner circumferential surface 12, also in thedirection of the axial component of the centrifugal force which actsupon the fibers 51. In this manner the control over the fibers 51 isnever lost. There is no uncontrolled hurling of the fibers 51, and thefibers 51 are therefore always kept in a scattered state by the airstream such as is necessary for their further processing and areimparted the required direction of movement.

The air stream transporting the fibers 51 moves also at the outlet fromthe fiber guiding element 8 in a rotational direction so that the radialcomponent of the centrifugal forces act upon the fibers 51. Here theforward end of every fiber 51 is transferred upon emerging from thefiber guiding element 8 to the rapidly moving gliding wall 22 of thespinning rotor while the air escapes through the gap between the openedge 9 of the spinning rotor 2 and the fiber guiding element 8 andthrough the air line 4. The velocities are selected so that therotational speed of the gliding wall 22 of the spinning rotor 2 is inany case greater than the velocity of the fibers 51 in that direction.In this manner, the forward ends of the fibers 51 are pulled along bythe friction of the fibers against the gliding wall 22, while the rearends of the fibers 51 are pressed against the inner circumferentialsurface 12 by the centrifugal forces. This leads to additionalstraightening of the fibers 51 before being deposited in the spinningrotor 2 and being incorporated into the end of the yarn 5.

As they leave the fiber guiding element 8, the fibers 51 are distributedover its entire circumference and reach one and the same contourline--in relation to the plane going through the fiber collection groove23--on the gliding wall 22 of the spinning rotor 2. It has been shownthat such a fiber deposit on one and the same contour line of thespinning rotor 2 leads to especially good results with regards to yarnquality, e.g. tear resistance, elasticity and uniformity.

As the above description shows, the device can be modified in many wayswithin the framework of the invention, e.g. by replacing certaincharacteristics by equivalents or by using them in differentcombinations. Nor is the manner important in which the air streamconveying the fibers 51 is produced in individual cases. Thus, it may beproduced by a source of negative pressure, as described, or by thespinning rotor 2 itself. In the first instance the housing 1 isconnected as shown to a source of negative pressure. The source ofnegative pressure may however remove the conveying air also directlyfrom the spinning rotor 2, e.g. through the shaft 7 of the spinningrotor 2 which would be a hollow shaft, or through a suction channelextending through the rotor cover 3 into the spinning rotor 2 (goingthrough the fiber guiding element 8). In the second instance,ventilation openings distributed in a circle are provided in thespinning rotor 2 to produce a negative pressure within the spinningrotor 2 as a result of its rotation. In both cases, it is howeveressential that this air stream be conveyed through the fiber guidingelement 8 to the interior of the spinning rotor 2.

If the spinning rotor 2 is provided with ventilation openings andproduces the negative spinning pressure itself due to its rotation, itis also possible to have air penetrate through the gap between the fiberguiding element 8 and the spinning rotor 2 into the interior of thespinning rotor 2. If the spinning rotor 2 is installed in a closedhousing (not shown), the air introduced into the spinning rotor 2through the gap may be the air which previously left the spinning rotor2 through its ventilation openings as a result of its rotation. If thechamber enclosed by the housing is subdivided, it is alternativelypossible for the air stream leaving the spinning rotor 2 through theventilation openings to be removed from the housing through a firstchamber, while another air stream is introduced into the gap and intothe spinning rotor 2 through a second chamber. In any case, care must betaken that the additional air fed to the spinning rotor through thefiber guiding element 8 is again removed from the latter. At least whenthe air leaving the spinning rotor 2 through the ventilation openingsreenters the spinning rotor 2 through the gap, an additional suctionmust be provided. This may be connected to the hollow shaft 7 of thespinning rotor 2, whereby the yarn draw-off pipe 6 then extendspreferably through the interior of the fiber guiding element 8 into thespinning rotor 2.

In the embodiment shown, the fiber guiding element 8 overlaps thespinning rotor 2 towards the inside. If air can be conveyed through thegap between spinning rotor 2 and fiber guiding element 8 into theinterior of the rotor, it may in some cases be possible to eliminate theoverlap of the fiber guiding element 8 since fiber loss is avoided bythe air flowing into the spinning rotor. The relative positions of theoutlet opening 10 and the open edge 9 of the spinning rotor 2 can beused to influence the orientation of the air flowing into the spinningrotor 2, and thereby the deposit of the individual fibers 51 on thegliding wall 22 of the spinning rotor 2.

It is not absolutely necessary to make the shaft 7 of the spinning rotor2 hollow, since the yarn draw-off pipe 6, in a variant from the shownembodiment, can also be taken through the rotor cover 3 (and through thefiber guiding element 8).

In the embodiment according to FIG. 1, the fiber guiding element 8 is anintegral part of the rotor cover 3. This makes it possible to achieveespecially low-cost fabrication. However, if different fiber guidingelements 8 are to be used optionally to adapt to different spinningconditions, it may be advantageous for the fiber guiding element 8 to beattached to the rotor cover 3 in such manner that it can be replaced.Here again different designs are of course possible, depending on theconfiguration of the rotor cover 3, etc. For example, the fiber guidingelement 8 may be installed on the side of rotor cover 3 towards thespinning rotor 2. If the fiber guiding element 8 has a greater axialextension, the rotor cover 3 may alternatively be provided with a recessinto which the fiber guiding element 8 is inserted. In this manner it ispossible to replace the fiber guiding element 8 easily and independentlyof the rotor cover 3 with a fiber guiding element 8 which is adapted ina special manner to the spinning rotor 2 to be used. It is also possibleto replace the fiber guiding element 8 when this is necessary because ofwear, without having to replaced the rotor cover 3 at the same time.

When the fiber guiding element 8 contains several longitudinal segments16 and 17 or 18 and 19 or else 18, 20 and 19 as shown in FIGS. 2b to 2d,such a replacement need not necessarily be made for the entire fiberguiding element 8. Depending on the reason for replacement it maysuffice if only the longitudinal segment 17 or 19 toward the spinningrotor is replaced, while the longitudinal segment 16 or 18 is notreplaced. In a fiber guiding element 8 with three or more longitudinalsegments, the middle segment 20 or the middle segments can also bereplaced if this is useful. Correspondingly, the fiber guiding element 8must then subdivided into two parts of which one contains at least thelongitudinal segment 16 or 18 with the outlet 13 of the fiber guidingelement 8 and can be excluded from the replacement (but need not be),while the other comprises at least the longitudinal segment 17 or 19 andcan be removed and replaced.

Such a replaceability of the parts of the fiber guiding element 8 isespecially advantageous when spinning rotors 2 with different diametersare used. The longitudinal segment 16 or 18 of the fiber guiding element8 remains unchanged, whatever the configuration or the size of thespinning rotor 2, so that the distance or the position of the opener andfeeding device 15 in relation to the spinning rotor 2 (or vice versa)need not be changed. Thus the geometric relationships between opener andfeeding device 15 and the fiber feeding channel 14 also remainunchanged. To adapt to a different rotor configuration or size, alongitudinal segment 17 or 19 (and possibly a longitudinal segment 20preceding it or several such intercalated longitudinal segments) isreplaced by an appropriately different divergence angle W1 so that thefiber guiding element 8 ends in any case in immediate proximity of thegliding wall 22 of the spinning rotor 2.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the scope or spirit of the invention. Forexample, features illustrated as part of one embodiment can be used onanother embodiment to yield a still further embodiment. It is intendedthat the present invention cover such modifications and variations ascome within the scope of the appended claims and their equivalents.

We claim:
 1. A device for feeding fibers from a fiber feeding channel toa fiber collection groove of an open-end spinning rotor having an openside which is covered by a rotor cover, said device comprising a fiberguiding element disposed opposite said open side of said rotor, saidfiber guiding element comprising an inner circumferential surfacedefining a fiber guiding surface, said fiber guiding surface divergingtowards said rotor and forming an opening angle in the direction of saidrotor, said fiber guiding element further comprising a tangentialopening defined in said fiber guiding surface, said opening tangentialwith respect to a spinning axis of said spinning rotor in a directioncorresponding to a rotational direction of said spinning rotor, saidfiber feeding channel in communication with said opening so that an airstream is produced and introduced tangentially into the fiber guidingelement in the direction of rotation of said spinning rotor, thetangential air stream carrying fibers tangentially to said fiber guidingsurface.
 2. The device as in claim 1, wherein said fiber guiding elementis defined within said rotor cover.
 3. The device as in claim 2, whereinsaid fiber guiding element is formed integral with said rotor cover. 4.The device as in claim 1, wherein said opening angle of said fiberguiding surface increases from said opening in the direction of saidrotor.
 5. The device as in claim 1, wherein said fiber guiding surfacewidens conically in the direction of said rotor.
 6. The device as inclaim 1, wherein said fiber guiding surface defines a continuous openingangle.
 7. The device as in claim 6, wherein said fiber guiding surfaceis uniformly convex.
 8. The device as in claim 1, wherein said fiberguiding surface defines a discontinuous opening angle.
 9. The device asin claim 8, wherein said fiber guiding surface comprises at least twolongitudinal segments defining different opening angles towards saidrotor.
 10. The device as in claim 9, wherein one of said longitudinalsegments adjacent said opening defines a conical surface.
 11. The deviceas in claim 9, wherein one of said longitudinal segments adjacent saidrotor defines a conical surface.
 12. The device as in claim 9, furthercomprising a third longitudinal segment between said two longitudinalsegments.
 13. The device as in claim 12, wherein said third longitudinalsegment defines a convex surface and said first and second longitudinalsegments define conical segments.
 14. The device as in claim 9, whereinsaid longitudinal segment adjacent said rotor is replaceable.
 15. Thedevice as in claim 11, wherein said fiber guiding element is disposed soas to extend into said rotor.